U.S. patent number 10,356,444 [Application Number 15/544,753] was granted by the patent office on 2019-07-16 for method and apparatus for encoding and decoding high dynamic range (hdr) videos.
This patent grant is currently assigned to InterDigital VC Holdings, Inc.. The grantee listed for this patent is THOMSON LICENSING. Invention is credited to Pierre Andrivon, Philippe Bordes, Edouard Francois, Sebastien Lasserre, Fabrice Leleannec.
United States Patent |
10,356,444 |
Leleannec , et al. |
July 16, 2019 |
Method and apparatus for encoding and decoding high dynamic range
(HDR) videos
Abstract
To preserve backward compatibility with a non-HDR device or
service, an HDR picture may be represented using a modulation value
and an SDR picture representative of the HDR picture. The
modulation value and the SDR picture can then be encoded into the
bitstream. At the receiving side, the modulation value and the SDR
picture can be decoded. Based on the modulation value, the SDR
picture can be mapped to a decoded HDR picture. For a non-HDR
device or service, the modulation value information may be
discarded and only the SDR picture is decoded. In particular, the
modulation value may be implicitly signaled, using quad-tree
representation information, intra coding information, inter
partition mode information or motion vector residual
information.
Inventors: |
Leleannec; Fabrice (Mouaze,
FR), Lasserre; Sebastien (Thorigne Fouillard,
FR), Andrivon; Pierre (Liffre, FR), Bordes;
Philippe (Laille, FR), Francois; Edouard (Bourg
des Comptes, FR) |
Applicant: |
Name |
City |
State |
Country |
Type |
THOMSON LICENSING |
Issy les Moulineaux |
N/A |
FR |
|
|
Assignee: |
InterDigital VC Holdings, Inc.
(Wilmington, DE)
|
Family
ID: |
52472264 |
Appl.
No.: |
15/544,753 |
Filed: |
January 29, 2016 |
PCT
Filed: |
January 29, 2016 |
PCT No.: |
PCT/EP2016/051868 |
371(c)(1),(2),(4) Date: |
July 19, 2017 |
PCT
Pub. No.: |
WO2016/120420 |
PCT
Pub. Date: |
August 04, 2016 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20170374390 A1 |
Dec 28, 2017 |
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Foreign Application Priority Data
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Jan 30, 2015 [EP] |
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15305112 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04N
19/463 (20141101); H04N 19/147 (20141101); H04N
19/139 (20141101); H04N 19/96 (20141101); H04N
19/467 (20141101); H04N 19/98 (20141101); H04N
19/122 (20141101); H04N 19/70 (20141101); H04N
19/186 (20141101); H04N 19/44 (20141101) |
Current International
Class: |
H04N
19/70 (20140101); H04N 19/96 (20140101); H04N
19/44 (20140101); H04N 19/186 (20140101); H04N
19/147 (20140101); H04N 19/139 (20140101); H04N
19/122 (20140101); H04N 19/467 (20140101); H04N
19/98 (20140101); H04N 19/463 (20140101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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WO2009045636 |
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Apr 2009 |
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WO |
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WO2013103522 |
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Jul 2013 |
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WO |
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Other References
Boyce et al.: Draft high efficiency video coding (HEVC) version 2,
combined format range extensions (RExt), Scalability (SHVC), and
multi-view (MV-HEVC) extensions, JCTVC-R1003_v6, Sapporo (JP), Jun.
2014. cited by applicant .
Segall, A, et al: "Tone mapping SEI",19. JVT Meeting; Mar. 31,
2006-Jul. 4, 2006;Geneva, CH; (Joint Video Team of ISO/IEC
JTCl/SC29/WGII and ITU-T SG.16 ), No. JVT-S087, Apr. 1, 2006 (Apr.
1, 2006). cited by applicant .
Yiqi Tew et al: "An Overview of Information Hiding in H.264/AVC
Compressed Video",IEEE Transactions on Circuits and Systems for
Video Technology,vol. 24, No. 2, Feb. 1, 2014 (Feb. 1, 2014), pp.
305-319. cited by applicant .
Kapotas S K, et al: "Data Hiding in H. 264 Encoded Video
Sequences",Multimedia Signal Processing, 2007. MMSP2007. IEEE 9th
Workshop on, IEEE,Piscataway, NJ, USA, Oct. 1, 2007 (Oct. 1, 2007),
pp. 373-376. cited by applicant.
|
Primary Examiner: Owens; Tsion B
Attorney, Agent or Firm: Dorini; Brian J. Lu; Xiaoan
Claims
The invention claimed is:
1. A method for generating a bitstream for a High Dynamic Range
(HDR) picture, comprising: determining a value indicative of
illumination information of the HDR picture; generating the
bitstream including a Standard Dynamic Range (SDR) picture
responsive to the HDR picture and the determined value, wherein
illumination values of the HDR picture are scaled down by the
determined value to form the SDR picture; and forcing a quad-tree
representation of a portion of the HDR picture to only contain
coding units (CUs) of a same size, wherein the determined value is
represented by a plurality of bits, and each of the plurality of
bits is used to determine whether a first transform size or a
second transform size is used for a corresponding CU of a plurality
of CUs in a portion of the SDR picture.
2. The method of claim 1, wherein the value indicative of
illumination information of the HDR picture is determined using an
average, median, minimum or maximum value of the luminance values
of the HDR picture.
3. The method of claim 1, wherein each one of the plurality of the
bits is encoded as a flag indicative of a transform size.
4. The method of claim 1, wherein the transform size is determined
for a first largest coding unit (LCU) of the SDR picture.
5. A method for decoding a bitstream including a High Dynamic Range
(HDR) picture, comprising: determining a value indicative of
illumination information of the HDR picture, wherein said value is
represented by a plurality of bits, and each of the plurality of
bits is determined from a flag indicating whether a first transform
size or a second transform size is used for a corresponding coding
unit (CU) of a plurality of CUs for a portion of a Standard Dynamic
Range (SDR) picture, wherein a quad-tree representation of the
portion of the SDR picture only contains coding units of a same
size; and determining the HDR picture responsive to the determined
value and the SDR picture included the bitstream, wherein the
illumination values of the SDR picture are scaled up by the
determined value to form the HDR picture.
6. The method of claim 5, wherein the determining a value
determines a plurality of values for a plurality of respective
spatial areas in the HDR picture.
7. The method of claim 5, wherein each one of the plurality of the
bits is decoded as a flag indicative of a transform size.
8. The method of claim 5, wherein each of the plurality of bits is
used to indicate the transform size for a respective one of a
plurality of coding units in a portion of the SDR picture.
9. The method of claim 5, wherein a syntax element is used to
indicate that the determined value is implicitly signaled.
10. The method of claim 5, wherein the determined value is
determined from a portion of the bitstream representative of a
first largest coding unit (LCU) of the SDR picture.
11. An apparatus for generating a bitstream for a High Dynamic
Range (HDR) picture, comprising at least one memory and one or more
processors, wherein the one or more processors are configured to:
determine a value indicative of illumination information of the HDR
picture; and generate the bitstream including a Standard Dynamic
Range (SDR) picture responsive to the HDR picture and the
determined value, wherein illumination values of the HDR picture
are scaled down by the determined value to form the SDR picture;
and forcing a quad-tree representation of a portion of the HDR
picture to only contain coding units (CUs) of a same size, wherein
the determined value is represented by a plurality of bits, and
each of the plurality of bits is used to determine whether a first
transform size or a second transform size is used for a
corresponding CU of a plurality of CUs in a portion of the SDR
picture.
12. The apparatus of claim 11, wherein each one of the plurality of
the bits is encoded as a flag indicative of a transform size.
13. The apparatus of claim 11, wherein the value is determined for
a first largest coding unit (LCU) of the SDR picture.
14. An apparatus for decoding a bitstream including a High Dynamic
Range (HDR) picture, comprising at least one memory and one or more
processors, wherein the one or more processors are configured to:
determine a value indicative of illumination information of the HDR
picture, wherein said value is represented by a plurality of bits,
and each of the plurality of bits is determined from a flag
indicating whether a first transform size or a second transform
size is used for a corresponding coding unit (CU) of a plurality of
CUs for a portion of a Standard Dynamic Range (SDR) picture,
wherein a quad-tree representation of the portion of the SDR
picture only contains coding units of a same size; and determining
the HDR picture responsive to the determined value and the SDR
picture included the bitstream, wherein illumination values of the
SDR picture are scaled up by the determined value to form the HDR
picture.
15. The apparatus of claim 14, wherein each one of the plurality of
the bits is decoded as a flag indicative of a transform size.
16. The apparatus of claim 14, wherein the value is determined from
a portion of the bitstream representative of a first largest coding
unit (LCU) of the SDR picture.
Description
This application claims the benefit, under 35 U.S.C. .sctn. 365 of
International Application PCT/EP2016/051868, filed Jan. 29, 2016,
which was published in accordance with PCT Article 21(2) on Aug. 4,
2016 in English and which claims the benefit of European
application No. 15305112.3, filed Jan. 30, 2015.
TECHNICAL FIELD
This invention relates to a method and an apparatus for encoding
and decoding a High Dynamic Range (HDR) video, and more
particularly, to a method and an apparatus for conveying
illumination information for an HDR video.
BACKGROUND
This section is intended to introduce the reader to various aspects
of art, which may be related to various aspects of the present
invention that are described and/or claimed below. This discussion
is believed to be helpful in providing the reader with background
information to facilitate a better understanding of the various
aspects of the present invention. Accordingly, it should be
understood that these statements are to be read in this light, and
not as admissions of prior art.
The dynamic range of luminance in a picture can be defined as a
ratio between the highest luminance value of an image and the
lowest luminance value of the image: r=bright/dark (1) where
"bright" denotes the highest luminance value of the image and
"dark" denotes the lowest luminance value of the image. The dynamic
range "r" is generally expressed as a number of power of two,
called f-stops or equivalently stops. For instance, a ratio 1000 is
about 10 f-stops, which is the typical dynamic range of standard
non-HDR videos, also called SDR (Standard Dynamic Range) videos or
equivalently LDR (Low Dynamic Range) videos.
Video signals used in the current consumer market are usually
represented by 8 bits, and can handle up to 10 f-stops as shown
below. An 8-bit video can represent a higher dynamic range than the
obvious 8 f-stops if the video signal is not represented linearly
but uses a non-linear dynamic compression curve. For instance,
applying a BT.709 OETF (Opto-Electronic Transfer Function) curve on
a linear light video signal, defined by the ITU-R and approximately
equivalent to a gamma (power function) 1/2.2 to 8-bit video
signals, would allow a dynamic range of more than 10 f-stops. In
particular, the inverse OETF curve is represented as
.ltoreq..ltoreq..gtoreq..gtoreq. ##EQU00001## on the input range
V.di-elect cons. [0,1]. The peak at V=1 outputs the brightest value
at L=1, and the lowest non-zero coded value V=1/255 outputs the
darkest value at L=0.00087. Thus, the dynamic range for an 8-bit
video signal using the OETF curve is r=1/0.00087=1147, roughly 10
f-stops. Since 8-bit video signals can have a dynamic range around
10 f-stops, an HDR video usually refers to a video with a dynamic
range noticeably higher than 10 f-stops.
The exact dynamic range that an HDR video application supports may
vary. For example, the SMPTE (Society of Motion Picture and
Television Engineers) defines a Perceptual Quantizer EOTF
(Electro-Optical Transfer Function) also known as PQ EOTF (defined
in SMPTE ST. 2084) non-linear transfer curve, preferably coded on
12 bits, which may code the luminance on the range from 0.005 nits
to 10000 nits (nit is a term referring to candela per square meter
units or cd/m.sup.2), leading to a ratio of 2 million or about 21
f-stops. Practically, first deployments of HDR at home may be
expected to be TV sets providing not much more than a peak
brightness of 1000 nits and a dynamic range of 15 f-stops,
preferably on 10 bits data format if possible. This restricted HDR
is also referred to as Extended Dynamic Range (EDR). Typically, an
SDR video has a bit depth of 8 or 10 bits, and an HDR video has a
bit depth of 10 bits and higher. For example, an SDR video can be a
4:2:0 Y'CbCr 10-bit video, and an HDR video can be a PQ OETF Y'CbCr
12-bit video.
SUMMARY
According to an aspect of the present principles, a method for
generating a bitstream for a High Dynamic Range (HDR) picture is
presented, comprising: determining a modulation value responsive to
the HDR picture; and generating the bitstream including a Standard
Dynamic Range (SDR) picture responsive to the HDR picture and the
determined modulation value, wherein the determined modulation
value is implicitly signaled in the bitstream.
According to another aspect of the present principles, a method for
decoding a bitstream including a High Dynamic Range (HDR) picture
is presented, comprising: determining a modulation value implicitly
signaled in the bitstream; and determining the HDR picture
responsive to the determined modulation value and a Standard
Dynamic Range (SDR) picture included the bitstream.
According to another aspect of the present principles, an apparatus
for generating a bitstream for a High Dynamic Range (HDR) picture
is presented, comprising: a processor configured to determine a
modulation value responsive to the HDR picture and generate the
bitstream including a Standard Dynamic Range (SDR) picture
responsive to the HDR picture and the determined modulation value,
wherein the determined modulation value is implicitly signaled in
the bitstream; and a communication interface configured to output
the bitstream.
According to another aspect of the present principles, an apparatus
for decoding a bitstream including a High Dynamic Range (HDR)
picture is presented, comprising: a communication interface
configured to access the bitstream; and a decoder configured to
determine a modulation value implicitly signaled in the bitstream
and determine the HDR picture responsive to the determined
modulation value and a Standard Dynamic Range (SDR) picture
included the bitstream.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates an exemplary SDR/HDR distribution workflow.
FIG. 2 illustrate an exemplary method for encoding an HDR video
according to an embodiment of the present principles.
FIG. 3 illustrate an exemplary method for decoding an HDR video
according to an embodiment of the present principles.
FIG. 4 illustrates pictorial examples of functions mapping HDR
luminance to SDR luminance according to an embodiment of the
present principles.
FIG. 5 illustrates a block diagram depicting an exemplary system in
which various aspects of the exemplary embodiments of the present
principles may be implemented.
FIG. 6 illustrates a block diagram depicting an example of a video
processing system that may be used with one or more
implementations.
FIG. 7 illustrates a block diagram depicting another example of a
video processing system that may be used with one or more
implementations.
FIG. 8A illustrates an exemplary first LCU (Largest Coding Unit) of
a picture to be encoded, which has a typical size of 64.times.64
pixels, and FIG. 8B illustrates an exemplary embodiment of
signaling the bits of the binary representation Ba_bin in an
implicit way according to an embodiment of the present
principles.
FIG. 9 is an exemplary pictorial example depicting the rate
distortion performance of the H.265/HEVC with and without the
proposed technique.
DETAILED DESCRIPTION
Many video coding standards and video codecs have been developed
for SDR videos, for example, but not limited to, MPEG-2, H.264/AVC,
H.265/HEVC standards and codecs that are conformed to these
standards. In the present application, the various encoders,
decoders and devices that support SDR videos, but not HDR videos,
are referred to as SDR (or non-HDR) encoders, decoders and devices,
respectively, and the various encoders, decoders and devices that
support HDR videos are referred to as HDR encoders, decoders and
devices, respectively. In the present application, we use the terms
"frame" and "picture" interchangeably to identify a sample array,
often containing values for multiple components.
When handling HDR videos, for example, encoding or distributing HDR
videos, it is desirable that the system can also provide backward
compatibility to the devices or services that only support SDR
videos. In the present application, we call a system that handles
HDR videos with backward compatibility with SDR videos as an
SDR/HDR system. In particular, with backward compatibility, an SDR
decoder within an SDR/HDR system should be able to generate an
associated SDR video representative of the HDR video, but with a
more limited dynamic range than the HDR video.
A straightforward solution of designing an SDR/HDR distribution
system could be simulcasting both SDR and HDR video streams on the
distribution infrastructure, which virtually doubles the needed
bandwidth compared to an infrastructure distributing only the SDR
videos. When the bandwidth is limited, the SDR/HDR distribution
system usually should take the bandwidth consumption into
consideration.
Another solution is to reduce the dynamic range of an HDR video
into a limited number of bits (for example, 10 bits) using a
non-linear function, compress the reduced HDR video (for example,
using the Main 10 profile of H.265/HEVC), and distribute the
compressed video stream. Exemplary non-linear functions for
reducing the dynamic range of an HDR video include PQ OETF, gamma
compensation curves and BT.709/BT.2020 OETF ITU-R curves. More
generally, an HDR video may be converted to an SDR video using an
"absolute" non-linear mapping curve, where "absolute" should be
understood as the mapped SDR value corresponds to a unique HDR
input brightness, i.e., the curve is not adapted to the content.
Using an "absolute" mapping curve, the reduced HDR video usually
does not provide a good viewability (i.e., preserve the overall
perceived brightness (i.e., dark vs. bright scenes) and perceived
colors (for instance, preservation of hues and perceived
saturation, also called colorfulness) of the corresponding HDR
video) as an SDR video, and thus this solution lacks backward
compatibility. In addition, the compression performance is usually
poor.
In view of the drawbacks in the existing solutions, we consider
that the following constraints should generally be taken into
account when designing an SDR/HDR distribution system with backward
compatibility with SDR devices and services: Minimizing the bitrate
of the SDR/HDR distribution system; Ensuring good quality of both
SDR and HDR decoded videos; Providing backward compatibility such
that the SDR video is decodable and viewable for users only having
access to SDR decoders; and Providing good viewability for the
decoded SDR video, in particular, the SDR video should preserve the
overall perceived brightness (i.e., dark vs. bright scenes) and
perceived colors (for instance, preservation of hues and perceived
saturation, also called colorfulness) of the corresponding HDR
video.
FIG. 1 illustrates an exemplary SDR/HDR distribution workflow 100
that transmits HDR videos while providing backward compatibility
with SDR decoders. In workflow 100, an HDR frame is processed to
obtain a corresponding SDR frame and illumination information
(110). For example, an illumination frame (also called illumination
map or backlight frame/image) can be determined from the HDR frame
to represent the backlight of the HDR content.
Here, the term backlight is used by analogy with TV sets made of a
color panel, such as an LCD panel, and a rear illumination
apparatus, such as an LED array. The rear apparatus, usually
generating white light, is used to illuminate the color panel to
provide more brightness to the TV. As a consequence, the luminance
of the TV is the product of the luminance of rear illuminator and
the luminance of the color panel. This rear illuminator is often
called "backlight."
Given the illumination frame, a residual frame (i.e., the SDR
frame) is then obtained by dividing the HDR frame by the
illumination map. Referring back to the analogy where HDR is equal
to SDR times backlight, the SDR frame could be understood as the
response of the (SDR) color panel. Subsequently, both the
illumination information and the SDR frame are encoded (120) into a
bitstream, using, for example, but not limited to, an H.264/AVC or
H.265/HEVC encoder.
When encoding an HDR frame using such an approach, the encoder
encodes two components: an SDR frame (the residual frame), which
may be a viewable frame, and associated HDR illumination
information. These two components may have different formats from
each other, for example, the associated illumination information
may be monochrome and the SDR frame may use a Y'CbCr or an RGB
format. Also, each component can have different formats (for
example, Y'CbCr, YUV, RGB and XYZ).
At the decoding side, the SDR frame can be decoded using an SDR
decoder for backward compatibility (130), which provides a decoded
SDR video as output. Alternatively, both the SDR frame and the
illumination information can be decoded using an HDR decoder (140).
Using the decoded SDR frame and illumination information, the SDR
frame can be mapped back to a decoded HDR frame (150). The mapping
from SDR to HDR (150) can also be performed by the HDR decoder
(140).
When the illumination information is represented by an illumination
map, different methods can be used to encode the illumination
information and the SDR frame. In one example, the encoder may
choose a frame packing approach, where the illumination map and the
SDR frame are placed together to form a single picture before
encoding.
In another example, the encoder may use auxiliary picture coding,
which may require for instance an SHVC (scalable HEVC) framework
even if only a single layer of coding is used, i.e., no scalable
layer is used. Unlike H.264/AVC, here, the SHVC standard is needed
only to define the auxiliary picture syntax as such pictures are
not defined in the non-scalable HEVC standard. Generally, auxiliary
pictures are defined in addition to the so-called "primary coded
pictures," which correspond to the main video of the content. In
one embodiment, the illumination map is encoded as an auxiliary
picture, while the SDR frame is conveyed as a corresponding primary
coded picture.
In yet another example, the encoder decouples the input HDR signal
format from the output SDR signal formats, and conveys the
indication of these two signal formats using the VUI (Video
Usability Information) and an accompanying SEI (Supplemental
Enhancement Information) message containing information needed for
reconstruction of the output HDR signal. Specifically, SEI message
embeds PSF (Point Spread Function) model, which needs an extra
processing step to reconstruct the illumination map from the PSF
model.
In the above, we discussed splitting an HDR video into two
components, namely, an SDR video and an associated illumination
map, in order to distribute the HDR video while preserving backward
compatibility. In another embodiment, we may determine only a
single modulation value (also called illumination value or
backlight value, denoted as Ba), rather than an illumination map,
for a whole frame. Based on the single modulation value, a
corresponding SDR frame may be obtained for an HDR frame, for
example, using a non-linear mapping function that basically
performs normalization by the modulation value and a logarithm
function. In one embodiment, the SDR luminance data may be
determined through a set of mappings L.sub.SDR=g(Ba,Y.sub.HDR) that
depends on the modulation value Ba and the input HDR luminance
Y.sub.HDR.
The mappings that depend on illumination information are "relative"
in the sense that several input HDR sample values can correspond to
a unique SDR mapped value depending on the value Ba. On the decoder
side, the de-mapping from SDR to HDR is performed using the
received Ba value and the inverse functions g.sup.-1(Ba,
L.sub.SDR). Note that in the present application, the mapping
process from the SDR to HDR video is also sometimes referred to as
"de-mapping".
Referring back to FIG. 1 as an exemplary SDR/HDR distribution
workflow, if a single modulation value is used, the workflow 100
would process an HDR frame to obtain the single modulation value as
the illumination information and an SDR frame based on the single
modulation value at 110.
FIG. 2 illustrates an exemplary method 200 for encoding an HDR
video according to the present principles. Method 200 starts at
step 205. At step 210, it determines a modulation value Ba for an
individual frame in the HDR video. Different methods can be used to
calculate the modulation value, for example, but not limited to,
using an average, median, minimum or maximum value of the HDR
luminance. These operations may be performed in the linear HDR
luminance domain Y.sub.HDR,lin or in a non-linear domain like
ln(Y.sub.HDR,lin) or Y.sub.HDR,lin.sup..gamma. with
.gamma.<1.
At step 220, based on the modulation value Ba, it maps the HDR
picture onto an SDR picture represented in a format compatible with
an SDR encoder. At step 230, it encodes the obtained SDR picture
and the modulation value Ba. At step 240, it checks whether more
frames in the HDR video need to be processed. If yes, it returns
control to step 210; otherwise, it outputs the bitstream at step
250. Method 200 ends at step 299.
FIG. 3 illustrate an exemplary method 300 for decoding an HDR video
according to the present principles. Method 300 starts at step 305.
At step 310, it accesses a bitstream, for example, one generated
according to method 200. At step 320, it decodes the bitstream to
obtain a decoded SDR picture and a modulation value for the
picture. At step 330, the decoded SDR picture is mapped to an HDR
picture based on the modulation value. The de-mapping (i.e.,
SDR-to-HDR mapping) process used at step 330 should be the inverse
of the HDR-to-SDR mapping processing (for example, the mapping used
at step 220), used at the encoder side. At step 340, it checks
whether more frames in the bitstream need to be processed. If yes,
it returns control to step 320; otherwise, it outputs the recovered
HDR video at step 350. Method 300 ends at step 399.
When the HDR bitstream is to be decoded by an SDR decoder, the
modulation value could be discarded and only the SDR video would be
decoded from the bitstream.
The steps in method 200 may proceed at a different order from what
is shown in FIG. 2, for example, step 240 may be performed before
step 230. That is, all frames in the HDR video would be processed
to get the modulation values for all frames and the associated SDR
video before they are encoded. Similarly, the steps in method 300
may proceed at a different order from what is shown in FIG. 3, for
example, step 340 may be performed before step 330. That is,
modulation values for all frames and an SDR video would be decoded
before the SDR to HDR mapping.
In one embodiment, the following mapping function can be used to
reduce the dynamic range and map an HDR picture to an SDR picture:
L.sub.SDR=g(Ba,Y.sub.HDR)=M.sub.SDRf(Y.sub.HDR/Ba)/f(P.sub.HDR/Ba)
(3) where P.sub.HDR is the peak luminance of the HDR workflow,
M.sub.SDR is the maximum SDR luma or luminance value, L.sub.SDR is
the luminance of the SDR picture, Y.sub.HDR is the luminance of the
HDR picture, and f( ) is a function. In one example, f can be a
Slog function of the form f(z)=a ln(b+z)+c with f(0)=0. (4)
Examples of mapping functions g(Ba,Y.sub.HDR) defined by f as a
Slog function are shown in FIG. 4 for a peak P.sub.HDR=5000 nits
and a mapping to an SDR video of 10 bits, i.e., M.sub.SDR=1023.
The inverse process (i.e., SDR to HDR mapping) at the decoder side
can then be derived as:
Y.sub.HDR=Ba.times.f.sup.-1(f(P.sub.HDR/Ba)L.sub.SDR/M.sub.SDR) (5)
where, in the case of the Slog function f, its inverse f.sup.-1 is
f.sup.-1(z)=exp((z-c)/a)-b. (6)
Given the dynamic reduction curve (i.e., HDR to SDR mapping), an
HDR picture can be reduced to an SDR picture by the following
steps: 1. Step 1: luminance dynamic range reduction. Reduction of
the HDR luminance Y.sub.HDR dynamic range to get luminance
L.sub.SDR, for example at 10 bits, can be performed as
L.sub.SDR=g(Ba,Y.sub.HDR); 2. Step 2: construction of two chroma
components U (or Cb) and V (or Cr). Similarly, HDR chroma
components can be reduced using U.sub.SDR=g(Ba.sub.U,U.sub.HDR) and
V.sub.SDR=g(Ba.sub.V,V.sub.HDR), where Ba.sub.U=Ba.sub.V=Ba in case
of a monochrome modulation value. This completes the mapping
process and the SDR video has three components: L.sub.SDR,
U.sub.SDR and V.sub.SDR. In another embodiment, one can reduce the
RGB.sub.HDR components by R.sub.SDR=g(Ba,R.sub.HDR),
G.sub.SDR=g(Ba,G.sub.HDR), B.sub.SDR=g(Ba,B.sub.HDR) and deduce
UV.sub.SDR as linear combinations of RGB.sub.HDR, similarly to what
is done in the standard SDR workflow by using the BT.709 or BT.2020
RGB to YUV matrices.
In the above, various numeric values are discussed in different
operations. These numeric values are for exemplary purposes and can
be adjusted based on applications. For example, when the SDR video
was discussed above mainly as a 10-bit video, the SDR video can
also take other dynamic ranges or bit depths. The techniques
according to the present principles are also not limited to the
color format of the HDR video or SDR video. For example, when the
mapping process was mainly discussed above using the YUV format,
the mapping can also be applied to other color formats, for
example, but not limited to, YCbCr, RGB and XYZ formats.
Modulation Value Signaling
To convey the modulation value, the modulation value is converted
to a binary representation Ba_bin through a conversion method. This
conversion may take the form of a simple scalar quantization of the
Ba value, followed by a unary binary representation of the
quantized value. This conversion may also consist in applying a
logarithm function followed by a quantization step.
In the following, we describe different methods that can be used to
signal the modulation value. The techniques according to the
present principles can be used in HDR video distribution for
example, using H.265/HEVC, H.264/AVC or any other video codecs, for
broadcast and OTT (Over The Top), which is backward compatible with
SDR.
Implicit Signaling
In one embodiment, the modulation value information may be "hidden"
in a coded stream. Consequently, the signaling of modulation value
information does not need new syntax elements or metadata.
In the following, we use the HEVC standard to illustrate how to
embed the modulation value information without introducing new
syntax elements. The embedding or hiding techniques can also be
applied to other video compression standards.
Using modulation value hiding, the SDR/HDR distribution may proceed
as follows at the encoder side:
(1) determine a modulation value Ba for each frame;
(2) optionally quantize the Ba value to represent Ba using a binary
string at a reduced number of bits;
(3) map, depending on Ba, each HDR picture onto an SDR picture
represented in a format compatible with an SDR encoder, for
example, 4:2:0 YUV 10 bits for UHDTV. If Ba value is quantized,
then the mapping will be based on the quantized Ba;
(4) encode the obtained SDR video by using the SDR encoder, where
at least one coded syntax element is used to encode both the SDR
picture in conformance with a current standard, and also to encode
a binary string representative of the Ba value; and
(5) distribute the bitstream of the obtained encoded SDR video.
At the decoder side, the HDR video can be decoded from a bitstream
as follows:
(1) decode the bitstream to retrieve the hidden modulation value Ba
for each frame and a decoded SDR video; and
(2) de-map the SDR video to an HDR video by applying the inverse of
the mapping from HDR to SDR.
If a non-HDR decoder is used to decode the bitstream, then the
decoder may not even know that there is a hidden modulation value
in the bitstream and the modulation value information is discarded
when decoding the SDR video.
In one embodiment, it is possible to hide the Ba value in the
quad-tree representation information used to represent the HEVC
Coding Units and Transform Units. This could be performed by
directly coding the bits representing Ba as transform tree
splitting flags in the HEVC bitstream.
Using H.265/HEVC as an example, we illustrate in FIG. 10 an
exemplary quad-tree representation, where a coding tree unit (CTU)
is split into coding units and transform units. As illustrated in
FIG. 10, a CTU is first divided into Coding Units (CU), in a
quad-tree way. The HEVC syntax associated with a given CU
indicates, among others, the coding mode (Intra, Inter, Skip), the
partition mode used to divide a CU into different Prediction Units
(PU), and the Transform Tree depth used to further split the CU
into transform units. Each CU is assigned a so-called partition
mode, which indicates the way a CU is divided into one or more
Prediction Unit. Each Prediction Unit is given a set of Intra or
Inter Prediction parameters (e.g., angular prediction direction for
an Intra CU, reference picture(s) and motion vector(s) for an Inter
CU). Furthermore, each CU is also divided into a so-called
transform tree. A transform tree consists in a quad-tree
representation of the transformed blocks contained in a CU. As
shown in FIG. 10, the transform tree (called RQT in FIG. 10) may
have several depth levels, since transform sizes from 4.times.4 up
to 32.times.32 are supported by HEVC.
The hidden Ba value, which typically occupies between 0 and 17 bits
of information at most, should usually be fully contained within
the compressed representation of the first coding tree unit (CTU),
also called LCU (Largest Coding Unit) of each coded picture. Thus,
as soon as an H.265/HEVC video decoder has processed the first LCU,
it can derive the modulation value and therefore perform the HDR
reconstruction of the LCU. This allows pipelining the HDR
reconstruction process with the H.265/HEVC decoding process in a
very efficient way. The decoder is able to fully process one LCU
before starting processing the following ones.
FIG. 8A shows an exemplary first LCU of a picture to be encoded,
which has a typical size of 64.times.64 pixels. According to the
quad-tree structure obtained by a rate distortion optimization
process, the LCU is divided into Coding Units (CU) of different
sizes.
FIG. 8B illustrates an exemplary embodiment of signaling the bits
of the binary representation Ba_bin in an implicit way. In one
embodiment, we force the LCU quad-tree representation to only
contain CUs of size 8.times.8. For each Coding Unit, either a
4.times.4 transform or an 8.times.8 transform may be used, based on
the binary representation Ba_bin. For example, to embed the binary
representation Ba_bin, an 8.times.8 transform size corresponds to a
bit equal to 0 in the Ba_bin binary string, and a 4.times.4
transform corresponds to a bit equal to 1. Consequently, the first
LCU of the picture, which would have been encoded as shown in FIG.
8A, is actually encoded with the forced structure as shown in FIG.
8B.
Note that an LCU is typically of a size of 64.times.64 pixels,
hence contains 64 Coding Units with size 8.times.8, as shown in
FIG. 8B. Therefore, a binary string of 64 bits can be embedded
using the proposed technique, which is sufficient for the binary
string (for example, at 17 bits) we want to transmit for Ba_bin.
According to one embodiment, once the decoder has decoded a
sufficient number of bits (e.g., 17) for the Ba_bin string, then
the decoding of these element completes. Similarly, on the encoder
side, once a sufficient number of bits has been inserted into the
H.265/HEVC bitstream to signal Ba_bin, then the encoder stops
imposing the above constraint on the coding parameter decision
process.
Using this approach, the rate distortion performance of the
H.265/HEVC coding may be affected slightly, with regards to the
first LCU of the picture, as illustrated in an exemplary rate
distortion curve in FIG. 9, where the theoretical rate distortion
function associated with the first LCU of the picture is drawn
(solid line), together with the rate distortion points that can be
achieved with an H.265/HEVC encoder with various coding parameters
(CU sizes, TU sizes, prediction mode). The theoretical rate
distortion function may be calculated based on the minimum
achievable rate under the constraint of a maximum distortion
level.
As can be seen from FIG. 9, the rate distortion point that would
have been chosen by the encoder without the proposed constraint
(cross embedded in a circle) lies near the convex hull of all
achievable points, which corresponds to the theoretical rate
distortion function. Here, as we impose constraints on the
quad-tree representation of an LCU, the coding of the first LCU
becomes sub-optimal. This is illustrated by the rate distortion
point (cross embedded in a square) that is finally used for the
coding of the LCU. The rate difference .DELTA.R between the optimal
rate distortion point (cross embedded in a circle) and the
sub-optimal point (cross embedded in a square) corresponds to the
overhead associated with hiding the Ba_bin information into the
bitstream. Hence it corresponds to the amount of bits which is
incurred for coding the Ba_bin element, according to the considered
embodiment.
As discussed above, the rate distortion performance of the
H.265/HEVC coding may be affected slightly, with regards to the
first LCU of the picture. However, since the quantization parameter
are unchanged compared to an H.265/HEVC encoder without Ba_bin
embedding, the pixel domain distortion in the concerned LCU is
impacted in a quite limited way. Also, since the process only
applies to the first LCU, the overall rate distortion performance
of the considered SDR/HDR coding system may be negligible for a
whole picture.
Other syntax elements of the H.265/HEVC standard may be used to
embed the Ba_bin information. For example, the signaling of the
intra prediction may be adapted to insert Ba_bin information in it.
This may be done by forcing a maximum CU size, as in the previous
embodiment, in order to ensure a minimum number of Coding Units in
the considered LCU. Then for Intra Coding Unit, the value of the
prev_intra_luma_pred_flag may be forced so as to indicate the value
of a bit in the Ba_bin binary string.
In H.265/HEVC, the prev_intra_luma_pred_flag syntax element
indicates whether one of the "most probable intra prediction modes"
is used for the intra prediction of a current prediction unit,
inside an Intra CU. If equal to 1, this means the intra prediction
direction is derived from a neighboring intra predicted prediction
unit. Otherwise, an intra prediction direction out of these most
probable intra directions is used for current Intra predicted
prediction unit.
Moreover, for Inter Coding Units, some Ba_bin value may be
contained in the partition mode, which indicates the prediction
unit shape. Additionally, if motion vector residual information is
present, this information may also be used to indicate values in
the Ba_bin. The motion vector residual information, or motion
vector difference information, specifies the differences between a
motion vector's components of a current inter predicted prediction
unit, and the components of the motion vector used to predict the
motion vector of current prediction unit.
When the modulation value information is "hidden" in the bitstream
as discussed above, an H.265/HEVC decoder not implementing the
proposed techniques can decode the SDR video, without even
realizing that the modulation values are embedded in the bitstream.
Advantageously, the coded modulation value is ignored by such
H.265/HEVC decoders, and thus the workflow can preserve full
backward compatibility. Moreover, the proposed approach also has
low computation complexity and only incurs a negligible extra
bandwidth requirement. Since the modulation value information is
embedded within the picture, it is also easy to synchronize the
picture information and the modulation value information.
The modulation value embedding and retrieval as discussed above
could be used at encoding and decoding HDR videos, for example, at
the encoding at step 230 of method 200, and at step 320 of method
300.
In one embodiment, an SEI message can be used to indicate the
presence of implicitly signaled Ba values for the current coded
picture. This typically takes the form of an minimum SEI message
made of only a payload type syntax element (e.g., as described in
section 7.3.5 of document JCTVC-R1013_v6, draft version of HEVC
edition 2). For example, this SEI payload type contains a
particular value that indicates that associated current coded
picture in the sequence contains some hidden information that can
be used to retrieve a single-value modulation information (e.g.,
payloadType==181).
Different from a method that signals the modulation value
explicitly, the SEI message here serves only to indicate the
presence of the modulation value Ba related hidden information in
the current coded picture, while in the explicit mode, an SEI
message with the Ba value is transmitted.
An exemplary syntax of such minimal SEI message is described in
TABLE 1.
TABLE-US-00001 TABLE 1 Modulation value presence SEI message syntax
modulation_value_present(payloadSize) { Descriptor }
Semantics: modulation_value_present: The modulation_value_present
SEI message indicates that the current coded picture contains a
modulation value hidden information in the bitstream, as shown in
Table 2.
TABLE-US-00002 TABLE 2 Persistence scope of SEI message SEI message
Persistence scope modulation value presence The access unit
containing the SEI message
According to another embodiment the modulation_value_present SEI
message is persistent for several consecutive pictures. This
persistence scope may be informatively described in a table (such
as table F.4 or D.1 of JCTVC-R1013_v6), as shown in TABLE 3 and
TABLE 4.
TABLE-US-00003 TABLE 3 Persistence scope of SEI message - variant 1
SEI message Persistence scope modulation value presence The CVS
containing the SEI message
TABLE-US-00004 TABLE 4 Persistence scope of SEI message - variant 2
SEI message Persistence scope modulation value presence One or more
pictures associated with the access unit containing the SEI
message
The syntax of modulation_value_present SEI message may be as
follows in order to explicitly manage temporal persistence of
modulation value presence (hidden in the bitstream), as shown in
TABLE 5 and TABLE 6.
TABLE-US-00005 TABLE 5 Persistence scope of SEI message - variant 3
SEI message Persistence scope modulation value presence Specified
by the syntax of the SEI message
TABLE-US-00006 TABLE 6 Modulation value presence SEI message syntax
- variant modulation_value_present( payloadSize ) { Descriptor
modulation_value_cancel_flag u(1) if(
!modulation_value_cancel_flag) { modulation_value_present_flag u(1)
modulation_value_persistence_flag u(1) } }
Semantics modulation_value_cancel_flag equal to 1 indicates that
the modulation_value_present SEI message cancels the persistence of
any previous modulation_value_present SEI message in the output
order that applies to the current layer.
modulation_value_cancel_flag equal to 0 indicates that
modulation_value_present SEI follows.
modulation_value_persistence_flag specifies the persistence of the
modulation_value_present SEI message for the current layer.
modulation_value_persistence_flag equal to 0 specifies that the
modulation_value_present applies to the current picture only. Let
picA be the current picture. modulation_value_persistence_flag
equal to 1 specifies that the modulation value presence persists
for the current layer in the output order until either of the
following conditions is true: A new CLVS of the current layer
begins. The bitstream ends. A picture picB in the current layer in
an access unit containing a modulation_value_present SEI message
applicable to the current layer is output for which
PicOrderCnt(picB) is greater than PicOrderCnt(picA), where
PicOrderCnt(picB) and PicOrderCnt(picA) are the PicOrderCntVal
values of picB and picA, respectively, immediately after the
invocation of the decoding process for picture order count for
picB. modulation_value_present_flag equal to 1 specifies that
modulation value is present and hidden in the picture coded
bitstream. modulation_value_present_flag equal to 0 specifies that
modulation value is not present in the picture coded bitstream.
When modulation_value_present_flag is not present,
modulation_value_present_flag is inferred equal to 0.
In another embodiment, modulation_value_present(payloadSize) as
shown in TABLE 6 may be defined without
modulation_value_present_flag syntax element.
According to another embodiment, the implicit signaling technique
described above is employed in order to encode several values
instead of a Ba value as described above. These several values are
adapted to the representation of an illumination map (also called
modulation picture or backlight picture), which is not necessarily
constant over the whole picture area. In that case, a series of
coefficients are encoded in the bitstream, in order for the decoder
side to reconstruct an illumination map. Typically, this takes the
form of some weighting coefficients, which are used to compute a
linear combination of 2D spatial function (called shape functions).
This linear combination computed by the decoder, may correspond to
the illumination map used thereafter to perform SDR-to-HDR
mapping.
According to another embodiment, the illumination map may be
defined with a constant value for a given spatial picture area, for
example, corresponding to a tile or a slice of the H.265/HEVC coded
picture. In that case, one Ba value may be implicitly signaled for
each picture area in the considered picture. Therefore, a Ba_bin
representation is obtained for each picture area, and is hidden in
the first LCU of the corresponding picture area, according to one
or more of the hiding techniques previously introduced.
When multiple Ba related values are to be inserted in the
bitstream, the hidden modulation values may be contained not only
in the first LCU of an H.265/HEVC compressed picture, but may also
be hidden in subsequent LCUs in the picture. The same H.265/HEVC
syntax element modification techniques (quad-tree representation,
intra prediction mode and motion vectors) can be used to hide these
multiple coefficients.
FIG. 5 illustrates a block diagram of an exemplary system in which
various aspects of the exemplary embodiments of the present
principles may be implemented. System 500 may be embodied as a
device including the various components described below and is
configured to perform the processes described above. Examples of
such devices, include, but are not limited to, personal computers,
laptop computers, smartphones, tablet computers, digital multimedia
set top boxes, digital television receivers, personal video
recording systems, connected home appliances, and servers. System
500 may be communicatively coupled to other similar systems, and to
a display via a communication channel as shown in FIG. 5 and as
known by those skilled in the art to implement the exemplary video
system described above.
The system 500 may include at least one processor 510 configured to
execute instructions loaded therein for implementing the various
processes as discussed above. Processor 510 may include embedded
memory, input output interface and various other circuitries as
known in the art. The system 500 may also include at least one
memory 520 (e.g., a volatile memory device, a non-volatile memory
device). System 500 may additionally include a storage device 540,
which may include non-volatile memory, including, but not limited
to, EEPROM, ROM, PROM, RAM, DRAM, SRAM, flash, magnetic disk drive,
and/or optical disk drive. The storage device 540 may comprise an
internal storage device, an attached storage device and/or a
network accessible storage device, as non-limiting examples. System
500 may also include an encoder/decoder module 530 configured to
process data to provide an encoded video or decoded video.
Encoder/decoder module 530 represents the module(s) that may be
included in a device to perform the encoding and/or decoding
functions. As is known, a device may include one or both of the
encoding and decoding modules. Additionally, encoder/decoder module
530 may be implemented as a separate element of system 500 or may
be incorporated within processors 510 as a combination of hardware
and software as known to those skilled in the art.
Program code to be loaded onto processors 510 to perform the
various processes described hereinabove may be stored in storage
device 540 and subsequently loaded onto memory 520 for execution by
processors 510. In accordance with the exemplary embodiments of the
present principles, one or more of the processor(s) 510, memory
520, storage device 540 and encoder/decoder module 530 may store
one or more of the various items during the performance of the
processes discussed herein above, including, but not limited to the
modulation value, the SDR video, the HDR video, equations, formula,
matrices, variables, operations, and operational logic.
The system 500 may also include communication interface 550 that
enables communication with other devices via communication channel
560. The communication interface 550 may include, but is not
limited to a transceiver configured to transmit and receive data
from communication channel 560. The communication interface may
include, but is not limited to, a modem or network card and the
communication channel may be implemented within a wired and/or
wireless medium. The various components of system 500 may be
connected or communicatively coupled together using various
suitable connections, including, but not limited to internal buses,
wires, and printed circuit boards.
The exemplary embodiments according to the present principles may
be carried out by computer software implemented by the processor
510 or by hardware, or by a combination of hardware and software.
As a non-limiting example, the exemplary embodiments according to
the present principles may be implemented by one or more integrated
circuits. The memory 520 may be of any type appropriate to the
technical environment and may be implemented using any appropriate
data storage technology, such as optical memory devices, magnetic
memory devices, semiconductor-based memory devices, fixed memory
and removable memory, as non-limiting examples. The processor 510
may be of any type appropriate to the technical environment, and
may encompass one or more of microprocessors, general purpose
computers, special purpose computers and processors based on a
multi-core architecture, as non-limiting examples.
Referring to FIG. 6, a data transmission system 600 is shown, to
which the features and principles described above may be applied.
The data transmission system 600 may be, for example, a head-end or
transmission system for transmitting a signal using any of a
variety of media, such as, satellite, cable, telephone-line, or
terrestrial broadcast. The data transmission system 600 also may be
used to provide a signal for storage. The transmission may be
provided over the Internet or some other network. The data
transmission system 600 is capable of generating and delivering,
for example, video content and other content.
The data transmission system 600 receives processed data and other
information from a processor 601. In one implementation, the
processor 601 generates the HDR video and/or represents an HDR
picture using a single modulation value and an SDR picture
representative of the HDR picture. The processor 601 may also
provide metadata to 600 indicating, for example, the function used
in the mapping curves or the values of constants.
The data transmission system or apparatus 600 includes an encoder
602 and a transmitter 604 capable of transmitting the encoded
signal. The encoder 602 receives data information from the
processor 601. The encoder 602 generates an encoded signal(s). Then
encoder 602 may use, for example, method 200 as described in FIG.
2.
The encoder 602 may include sub-modules, including for example an
assembly unit for receiving and assembling various pieces of
information into a structured format for storage or transmission.
The various pieces of information may include, for example, coded
or uncoded video, and coded or uncoded elements. In some
implementations, the encoder 602 includes the processor 601 and
therefore performs the operations of the processor 601.
The transmitter 604 receives the encoded signal(s) from the encoder
602 and transmits the encoded signal(s) in one or more output
signals. The transmitter 604 may be, for example, adapted to
transmit a program signal having one or more bitstreams
representing encoded pictures and/or information related thereto.
Typical transmitters perform functions such as, for example, one or
more of providing error-correction coding, interleaving the data in
the signal, randomizing the energy in the signal, and modulating
the signal onto one or more carriers using a modulator 606. The
transmitter 604 may include, or interface with, an antenna (not
shown). Further, implementations of the transmitter 604 may be
limited to the modulator 606.
The data transmission system 600 is also communicatively coupled to
a storage unit 608. In one implementation, the storage unit 608 is
coupled to the encoder 602, and stores an encoded bitstream from
the encoder 602. In another implementation, the storage unit 608 is
coupled to the transmitter 604, and stores a bitstream from the
transmitter 604. The bitstream from the transmitter 604 may
include, for example, one or more encoded bitstreams that have been
further processed by the transmitter 604. The storage unit 608 is,
in different implementations, one or more of a standard DVD, a
Blu-Ray disc, a hard drive, or some other storage device.
Referring to FIG. 7, a data receiving system 700 is shown to which
the features and principles described above may be applied. The
data receiving system 700 may be configured to receive signals over
a variety of media, such as storage device, satellite, cable,
telephone-line, or terrestrial broadcast. The signals may be
received over the Internet or some other network.
The data receiving system 700 may be, for example, a cell-phone, a
computer, a set-top box, a television, or other device that
receives encoded video and provides, for example, decoded video
signal for display (display to a user, for example), for
processing, or for storage. Thus, the data receiving system 700 may
provide its output to, for example, a screen of a television, a
computer monitor, a computer (for storage, processing, or display),
or some other storage, processing, or display device.
The data receiving system 700 is capable of receiving and
processing data information. The data receiving system or apparatus
700 includes a receiver 702 for receiving an encoded signal, such
as, for example, the signals described in the implementations of
this application. The receiver 702 may receive, for example, a
signal providing one or more of the HDR and SDR videos, or a signal
output from the data transmission system 600 of FIG. 6.
The receiver 702 may be, for example, adapted to receive a program
signal having a plurality of bitstreams representing encoded HDR
pictures. Typical receivers perform functions such as, for example,
one or more of receiving a modulated and encoded data signal,
demodulating the data signal from one or more carriers using a
demodulator 704, de-randomizing the energy in the signal,
de-interleaving the data in the signal, and error-correction
decoding the signal. The receiver 702 may include, or interface
with, an antenna (not shown). Implementations of the receiver 702
may be limited to the demodulator 704.
The data receiving system 700 includes a decoder 706. The receiver
702 provides a received signal to the decoder 706. The signal
provided to the decoder 706 by the receiver 702 may include one or
more encoded bitstreams. The decoder 706 outputs a decoded signal,
such as, for example, decoded video signals including video
informations.
The data receiving system or apparatus 700 is also communicatively
coupled to a storage unit 707. In one implementation, the storage
unit 707 is coupled to the receiver 702, and the receiver 702
accesses a bitstream from the storage unit 707. In another
implementation, the storage unit 707 is coupled to the decoder 706,
and the decoder 706 accesses a bitstream from the storage unit 707.
The bitstream accessed from the storage unit 707 includes, in
different implementations, one or more encoded bitstreams. The
storage unit 707 is, in different implementations, one or more of a
standard DVD, a Blu-Ray disc, a hard drive, or some other storage
device.
The output data from the decoder 706 is provided, in one
implementation, to a processor 708. The processor 708 is, in one
implementation, a processor configured for performing the SDR to
HDR mapping. In some implementations, the decoder 706 includes the
processor 708 and therefore performs the operations of the
processor 708. In other implementations, the processor 708 is part
of a downstream device such as, for example, a set-top box or a
television.
The implementations described herein may be implemented in, for
example, a method or a process, an apparatus, a software program, a
data stream, or a signal. Even if only discussed in the context of
a single form of implementation (for example, discussed only as a
method), the implementation of features discussed may also be
implemented in other forms (for example, an apparatus or program).
An apparatus may be implemented in, for example, appropriate
hardware, software, and firmware. The methods may be implemented
in, for example, an apparatus such as, for example, a processor,
which refers to processing devices in general, including, for
example, a computer, a microprocessor, an integrated circuit, or a
programmable logic device. Processors also include communication
devices, such as, for example, computers, cell phones,
portable/personal digital assistants ("PDAs"), and other devices
that facilitate communication of information between end-users.
Reference to "one embodiment" or "an embodiment" or "one
implementation" or "an implementation" of the present principles,
as well as other variations thereof, mean that a particular
feature, structure, characteristic, and so forth described in
connection with the embodiment is included in at least one
embodiment of the present principles. Thus, the appearances of the
phrase "in one embodiment" or "in an embodiment" or "in one
implementation" or "in an implementation", as well any other
variations, appearing in various places throughout the
specification are not necessarily all referring to the same
embodiment.
Additionally, this application or its claims may refer to
"determining" various pieces of information. Determining the
information may include one or more of, for example, estimating the
information, calculating the information, predicting the
information, or retrieving the information from memory.
Further, this application or its claims may refer to "accessing"
various pieces of information. Accessing the information may
include one or more of, for example, receiving the information,
retrieving the information (for example, from memory), storing the
information, processing the information, transmitting the
information, moving the information, copying the information,
erasing the information, calculating the information, determining
the information, predicting the information, or estimating the
information.
Additionally, this application or its claims may refer to
"receiving" various pieces of information. Receiving is, as with
"accessing", intended to be a broad term. Receiving the information
may include one or more of, for example, accessing the information,
or retrieving the information (for example, from memory). Further,
"receiving" is typically involved, in one way or another, during
operations such as, for example, storing the information,
processing the information, transmitting the information, moving
the information, copying the information, erasing the information,
calculating the information, determining the information,
predicting the information, or estimating the information.
As will be evident to one of skill in the art, implementations may
produce a variety of signals formatted to carry information that
may be, for example, stored or transmitted. The information may
include, for example, instructions for performing a method, or data
produced by one of the described implementations. For example, a
signal may be formatted to carry the bitstream of a described
embodiment. Such a signal may be formatted, for example, as an
electromagnetic wave (for example, using a radio frequency portion
of spectrum) or as a baseband signal. The formatting may include,
for example, encoding a data stream and modulating a carrier with
the encoded data stream. The information that the signal carries
may be, for example, analog or digital information. The signal may
be transmitted over a variety of different wired or wireless links,
as is known. The signal may be stored on a processor-readable
medium.
* * * * *